Device for gripping and installing wire

ABSTRACT

A wire pulling grip easy and reliably grips wire for pulling the same through a conduit or the like. The grip has cams which maintain contact with the wire even when tension is not applied and regardless of the orientation of the grip, significantly reducing the likelihood that the connection with the wire is lost. The cams are selectively releasable to allow the wire to be easily removed from the grip.

RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 61/034,095, filed Mar. 5, 2008, which is expresslyincorporated herein in its entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to installing wire, cables (such as fiberoptic cables or communications cables), or the like. More specifically,the present invention relates to a device for gripping a wire, cable, orsimilar object so as to enable that object to be pulled through aconduit or other enclosure to install the object.

2. State of the Art

Wires, cables, and the like are commonly installed by pulling the samethrough a conduit. Industrial or commercial construction of buildingscommonly involves placing conduits in the walls of the building andinstalling wires or cables in the conduit after construction of the wallhas been completed. Similarly, municipal wires and cables are oftenpulled through underground conduits in order to install the cables.Herein, the term wire is used to describe the various types of wires,cables, and the like which are similarly pulled through conduits toinstall the same.

When installing wires, a rope or other pulling line is first threadedthrough the conduit. One end of the pulling line is then connected tothe wire, and a pulling machine is attached to the other end of thepulling line and used to pull the wire through the conduit via thepulling line. The pulling machine will typically exert a force of athousand pounds or more in order to pull the wire through the conduit.Lengthy conduits, bends in the conduit, and the stiffness of the wireitself all contribute to the high pulling force required to pull wiresthrough a conduit.

In municipal applications such as underground power lines orcommunications lines, the wires being installed are typically largerthan those used in commercial buildings, and require a very high pullingforce in order to successfully install the desired wire into theconduit.

When installing a wire, it is highly desirable to successfully installthe wire without losing the connection between the pulling line and theinstalled wire. If the connection between the pulling line and installedwire is lost during a pull, it is typically impossible to reconnect thewire and pulling line inside of the conduit. As such, the wire must beremoved from the conduit and the pull must be started again from thebeginning. It is typically impossible to remove the wire from theconduit without damaging the wire. Because of the space constraints(especially in underground municipal applications), it is typicallynecessary to attach a pulling line to the wire every few yards while thewire is pulled a section. Attachment to the wire typically pierces theinsulation or otherwise damages the wire and renders the wire unusable.Where multiple wires are being pulled at once through a conduit, all ofthe wires must be removed from the conduit and are typically thereafterunusable.

It is thus appreciated that losing connection between the pulling lineand the wire results in both a significant loss of time and asignificant monetary loss in the unusable wire. The larger wires used inmunicipal installations may cost several thousands of dollars for asingle run of wire. It can be appreciated that it is necessary to have asecure and reliable connection between the pulling line and theinstalled wire.

It is also necessary to have a connection between the pulling line andinstalled wire which is able to reliably transmit thousands of pounds offorce between the pulling line and the installed wire. It is desirablethat the connection between the pulling line and installed wire be ableto remain connected throughout the pull even if tension is temporarilylost or varies through out the pull, and should be able to remainconnected regardless of the orientation of the connection between thepulling line and wire. It is particularly desirable to have a connectorwhich remains easy and convenient to use while providing a secureattachment capable of transmitting a very high force to the wire.

It is thus desirable to have a connector which is capable of connectinga pulling line and a wire securely and reliably. It is desirable to havea connector which is capable of transmitting very high pulling forcesbetween the pulling line and wire reliably. It is desirable to have aconnector which remains securely connected to the pulling line and wireeven if tension is lost and regardless of the orientation of theconnector. It is desirable to have a connection which remains easy touse while providing a more secure and reliable operation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedconnector for connecting a pulling line to a wire for pulling the wirethrough a conduit.

According to one aspect of the invention, a connector is provided whichreleasably grips a wire. The connector may be provided with a bodythrough which the wire passes and a plurality of cams to grip the wire.The cams allow the wire to be easily passed in one direction through thebody, but grip the wire to prevent movement of the wire in the opposingdirection so as to transmit a pulling force to the wire.

According to another aspect of the invention, the cams are biasedtowards the center of the body in a position to grip the wire. The camsare biased towards a wire which is placed through the body of theconnector so that the cams remain in contact with the wire even iftension is not applied to the wire and regardless of the orientation ofthe connector.

According to another aspect of the invention, the biasing element whichbiases the cams towards the center of the body is movable so as to allowthe cams to move away from the center of the body in an unbiased manner.This allows the grip on the wire to be selectively released to allow thewire or a foreign object to be removed from the connector.

According to another aspect of the invention, a connector is providedwhich includes a body having cams therein for gripping the wire, andwhich also includes a Kellum grip attached thereto. The free end of theKellum grip is attached to the pulling line. The Kellum grip, whenplaced in tension, grips the wire and is capable of applying a verylarge pulling force to the wire. The connector body secures theconnector end of the Kellum grip to the wire so that the Kellum grip isplaced in tension when the pulling line is connected to the free end ofthe Kellum grip and tension applied thereto.

These and other aspects of the present invention are realized in adevice for pulling wire or the like as is shown and described in thefollowing figures and related description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are shown and described inreference to the numbered drawings wherein:

FIG. 1 shows a side view of a wire gripping device of the presentinvention;

FIG. 2 shows an end view of the distal end of the device of FIG. 1;

FIG. 3 shows an end view of the proximal end of the device of FIG. 1;

FIGS. 4A and 4B show side and end views of the spacer busing of thedevice of FIG. 1; and

FIG. 5 shows a side view of the device of FIG. 1.

It will be appreciated that the drawings are illustrative and notlimiting of the scope of the invention which is defined by the appendedclaims. The embodiments shown accomplish various aspects and objects ofthe invention. It is appreciated that it is not possible to clearly showeach element and aspect of the invention in a single figure, and assuch, multiple figures are presented to separately illustrate thevarious details of the invention in greater clarity. Similarly, notevery embodiment need accomplish all advantages of the presentinvention.

DETAILED DESCRIPTION

The invention and accompanying drawings will now be discussed inreference to the numerals provided therein so as to enable one skilledin the art to practice the present invention. The drawings anddescriptions are exemplary of various aspects of the invention and arenot intended to narrow the scope of the appended claims.

Turning now to FIG. 1, a side view of a wire pulling grip 10 is shown.In discussing the grip 10, exemplary sizes are given to promoteunderstanding of the grip. It will be appreciated, however, that varioussizes of the grip 10 are made to allow a wide variety of sizes of wireto be pulled with the grip. The grip 10 includes a body 14 having a bore18 therethrough. The body 14 is about 1.5 inches in diameter, and thebore 18 through the body is about 1.1 inches in diameter. The body 14has a distal end 14 a and a proximal end 14 b.

A plurality of cams 22 (four are used in the present embodiment,although smaller or larger sizes may use fewer or additional cams) arepivotably mounted to the body 14. The cams 22 pass through slots 26 inthe body 14 to allow the cams to pivot inwardly towards the center ofthe bore 18 or outwardly to extend out from the body. The cams 22 aremounted to a rolled ring 30 which is circular in shape and cross sectionand which forms a pivot for the cams. The ring 30 is typically made witha small gap to allow the cams 22 to be placed thereon. The ring fits ina shoulder or groove 34 which is formed in the body 14.

A spacer bushing 38 is installed against the ring 30 to hold the ring inplace in the body. The spacer bushing 38 has a tab or post 42 formed ona side thereof which passes through the gap in the ring 30 and fits intoa notch 46 formed in the body 14 to prevent rotation of the ring 30 andspacer bushing 38 to prevent loss of the cams 22. A spring clip 50 fitsagainst the spacer bushing 38 and into a groove 54 in the body 14 andlocks the spacer bushing 38 and ring 30 in place.

An elastic ring 58 (which could be a rubber ring, a circular spring,etc.) is placed around the body 14 in a sloped portion 62 of the body.The slope urges the elastic ring 58 towards the pivot ring 30, biasingthe cams 22 towards the center of the body 14. Additionally, anyfriction on the elastic ring 58 while pulling wires through a conduitwill also tend to bias the elastic ring 58 towards the pivot ring 30. Ifthe cams 22, sloped portion 62, and elastic ring 58 are appropriatelysized, the cams 22 will be biased completely to the center of the bore18. In operation, the cams 22 are thus biased towards a wire which isplaced through the bore 18, and are held in contact with the wire. Thisensures that the grip 10 does not lose connection with the wire if apulling force is not applied to the grip 10, if the pulling force istemporarily lost, or if the grip 10 is placed in any physicalorientation.

In use, the grip 10 is pulled in the direction of arrow 66. Resistanceto moving the wire which is being pulled by the grip 10 will cause thecams 22 to rotate inwardly towards the center of the bore 18 and thusincrease the force by which the wire is gripped. A high degree of forcecan be reliably applied to the wire as the cams 22 maintain contact andtighten with the application of force. In use, the grip 10 is connectedto a pulling line, a wire is passed through the body 14 through thedistal end 14 a of the grip in the direction of arrow 70, and the grip10 and wire are pulled in the direction of arrow 66.

Typically, the grip 10 is used in combination with a wire Kellum grip. AKellum grip is a tube made of braided wires. The tube is loosely braidedso that it increases diameter when compressed and decreases diameterwhen stretched. As such, the tube compresses around a wire or cable whenplaced in tension. Conventional Kellum grips are simply a braided tubeof wire with a loop formed on one end to attach to the pulling line. Theopen end of the tube is placed over the wire, secured to the wire(usually with duct tape or the like), and the Kellum grip is then usedto pull the wire. The problem with conventional Kellum grips is thedifficulty in securing the open end of the tube to the wire.

Typically, duct tape or the like is used to secure the open end of thetube to a wire. The duct tape, however, can be difficult to removeafterwards and may leave an undesirable residue on the wire or Kellumgrip. Additionally, there is some risk that the duct tape peels off ofthe grip/wire during a pull and begins to stick to the conduit, whichmay remove the tape completely and result in the loss of connectionbetween the wire and grip.

In order to be utilized in combination with a Kellum type grip, theproximal end 14 b of the body 14 has holes 74 and a groove 78 formedtherein. The holes 74 are spaced around the edge of the body 14 and arein communication with the groove 78 to allow wires to be lacedtherethrough without overly protruding radially from the body 14. Thegrip 10 with the Kellum grip attached therethrough is shown in FIG. 5.

Turning now to FIG. 2, an end view of the distal end 14 a of the grip 10is shown. The spring clip 50 and spacer bushing 38 are visible, as wellas the cams 22. The cams are biased into the bore 18 in the positionshown by the elastic ring 58. It can be seen how the cams 22 extendalmost completely into the center of the bore 18, and would maintaincontact with a wire of approximately 0.125 inch diameter while stillaccommodating a wire of about 1 inch diameter. The grip 10 is thususable with many sizes of wire.

Turning now to FIG. 3, an end view of the proximal end 14 b of the grip10 is shown. It can be seen how the holes 74 are spaced around the body14. The holes 74 accommodate wires to attach a Kellum grip to the body14.

Turning now to FIGS. 4A and 4B, side and end views of the spacer bushing38 are shown. As discussed, the spacer bushing 38 includes a post 42which is received in a notch 46 in the body 14 to prevent rotation ofthe spacer bushing 38 and pivot ring 30 and loss of the cams 22. Thespacer bushing 38 may also be made with notches 82 which receive thecams 22, allowing a closer fit between the spacer bushing 38 and cams22.

Turning now to FIG. 5, a side view of the grip 10 combined with abraided wire tube 86 (such as a Kellum grip) is shown. For clarity, manystructures shown in the previous figures are not numbered, but areunderstood to be present in the figure. The Kellum grip 86 includes aplurality of wires 90 which are braided together into a tube asdiscussed. The wires 90 are laced through the holes 74 (FIG. 1) in thegrip 10. The groove 78 keeps the wires 90 from protruding too farradially from the body 14. The wires 90 are typically formed into orconnected to a loop 94 which is connected to a pulling line. Thus, thebore or lumen formed by the braided tube of wires does not typicallyextend completely through the wires 90, but is closed at the proximalend of the wires by the loop 94.

In use, a wire is passed through the distal end 14 a of the body 14,passed through the bore 18 (FIG. 1), and is passed through the center ofthe braided wire grip 86 in the direction of arrow 70. The wire ispassed through the center of the braided wires 90. The cams 22, biasedby the elastic ring 58, maintain contact with the wire and preventmovement of the wire in the opposite direction. The loop 94 is thenconnected to a pulling line and the pulling line is used to pull thegrip 10 and wire through a conduit. The grip 10 secures the distal end14 a of the Kellum grip 86 to the wire, and both the grip 10 and Kellumgrip 86 transmit pulling force to the wire.

When a pull is completed, the grip 10 and Kellum grip 86 are easilyremoved from the wire. The elastic ring 58 is moved adjacent to thegroove 78, allowing the cams 22 to pivot away from the wire. The cams 22can then freely pivot out of the bore 18. The grip 10 and Kellum grip 86are simply slid off of the wire in the direction of arrow 70. The grip10 with Kellum grip 86 is thus advantageous as it is easily and quicklyinstalled and removed from a wire while being capable of transmittingwell over 10,000 pounds of force to the wire. In testing the pullingcapability of the grip 10 and Kellum grip 86, the observed mode offailure has been the wires 90 breaking, suggesting that nearly anyneeded pulling force may be supplied if the wires 90 are sizedappropriately.

The grip 10 provides an additional level of safety and convenience inuse as compared to existing wire pulling grips. There are known wirepulling grips which use teeth mounted in a tubular body to secure andpull a wire. The wire is inserted into the body and the teeth allow formovement of the wire in only one direction. After the pull is completed,the wire must be cut and passed through the body in the direction ofloading. These grips require that the person installing the wire cut thewire, remove a cap/pulling eyelet from the body, pass the cut portion ofwire through the body, and reattach the cap before starting anotherpull. This results in lost time. Additionally, if a person accidentallyplaces a tool or finger inside of the body, the object must be similarlyremoved. Where a finger is placed in the body, it is quite difficult toremove the finger without damage to the finger as the teeth preventwithdrawal of the finger. Thus, the grip 10 is much easier to use thanavailable prior art grips.

Additionally, the combination of the grip 10 and the braided wire tube86 provides significant advantages over prior art configurations. Wherebraided wire tubes, such as Kellum grips, are used, the Kellum grip isdifficult to use. As has been discussed, duct tape or the like istypically used to attach the distal end of the Kellum grip to the wire.The duct tape, however, has limited ability to secure the Kellum gripwires to the wire which is being pulled. As a result, the duct tape mayallow the Kellum grip to slip off of the wire which is pulled if toohigh of a pulling force is applied. Additionally, the duct tape will rubagainst the conduit as the wire is pulled therethrough, which may causethe leading edge of the tape to roll back and expose the adhesive of thetape. The exposed adhesive will then stick to the conduit and may causethe duct tape to be removed entirely. Either of these situations mayresult in a loss of connection with the wire which is being pulledthrough a conduit. Efforts to more securely attach a Kellum grip to thewire take additional setup time and additional time to remove the Kellumgrip from the wire, reducing the working speed and efficiency of thepersons installing wire. Thus, the pulling force which is applied to aKellum type grip is limited, and the use of the Kellum grip to pullwires has some risk of losing connection with the wire which is beingpulled.

The present invention, however, provides significant advantages when agrip 10 is combined with a Kellum type braided wire tube as shown inFIG. 5. As has been discussed above, the grip 10 provides a secureconnection with the wire which will transmit a significant pulling forceto the wire. Loss of connection between the grip 10 and the wire isvirtually eliminated altogether. Since the grip 10 does not loseconnection with the wire, the braided wire grip portion 86 also does notlose connection with the wire. The combined wire pulling grip is thusvery reliable as loss of connection with the wire is virtuallyeliminated.

Additionally, the combination of grip 10 and braided wire tube 86transmits a very high degree of force to the wire. While cams and spikestransmit force to a wire at a few points which are close together, thecombined grip transmits pulling force to a longer length of the wire atmany locations along the wire. Thus, a very high pulling force istransmitted to the wire without concentrating the force on only a fewlocations on the wire. Placing the entire pulling force at only a fewlocations on the wire may result in failure of the wire itself. Testingof the grip 10 and braided wire tube 86 as shown in FIG. 5 hasdemonstrated that failure of the grip occurs at failure of theindividual wires 90 rather than failure of the wire which is pulled or aloss of connection between the wire and the pulling grip. Thus, manythousands of pounds of force are reliably transmitted to the wire whichis pulled.

The grip 10 and braided wire tube 86 are also significantly easier touse than previous wire pulling grips. Previous wire pulling grips haverequired a significant amount of work to install and remove the gripfrom the wire, and often result in a loss in productivity. Thus, whileprior art designs have been a tradeoff between ease of use andreliability/pulling strength, the pulling grip of the present inventionmaximizes pulling strength and reliability while being extremely quickand easy to use.

There is thus disclosed an improved wire pulling grip. It will beappreciated that numerous changes may be made to the present inventionwithout departing from the scope of the claims.

1. A wire pulling grip comprising: a body having a bore through which awire may be passed, the body encompassing the bore; a plurality of camspivotably attached to the body, the plurality of cams being pivotablerelative to the body between a first position where the plurality ofcams extend into the bore of the body so as to grip the wire inserted ina first direction into the bore of the body and a second position wherethe plurality of cams extend outwardly from the body so as to releasethe wire to withdraw the wire from the bore of the body in a seconddirection opposite the first direction; and a biasing element whichbiases the plurality of cams into the first position.
 2. The wirepulling grip of claim 1, wherein the biasing element is selectivelymovable between a first position adjacent the plurality of cams tocontact and apply a force to the plurality of cams to bias the pluralityof cams into the bore of the body and a second position away from theplurality of cams so that the biasing element does not contact theplurality of cams and does not apply the force to the plurality of cams.3. The wire pulling grip of claim 1, wherein the biasing element is aring which extends around an outside of the body and contacts theplurality of cams.
 4. The wire pulling grip of claim 1, wherein thebiasing element is disposed on an exterior portion of the body which istapered so as to slope towards a pivot of the plurality of cams.
 5. Thewire pulling grip of claim 1, further comprising a tube formed of aplurality of inter-woven wires, the tube comprising: a first endattached to the body such that the wire may be passed through the bodyand into a lumen defined by the tube; and a second end attachable to apulling line.
 6. The wire pulling grip of claim 1, wherein the bodyfurther comprises a plurality of slots formed therein, and wherein eachof the plurality of cams is disposed in one of the plurality of slots,and wherein the plurality of cams are pivotable so as to pass throughthe plurality of slots.
 7. The wire pulling grip of claim 6, wherein thebiasing element extends around an exterior of the body and contacts theplurality of cams.
 8. The wire pulling grip of claim 1, wherein theplurality of cams are disposed radially about a single point along thelength of the body.
 9. A wire pulling grip comprising: a generallytubular body having a bore therethrough, the body encompassing the bore;a plurality of cams pivotably attached to the generally tubular body,the plurality of cams being pivotable relative to the generally tubularbody between a first position where the plurality of cams extend intothe bore of the generally tubular body so as to grip a wire inserted ina first direction into the bore of the generally tubular body and asecond position where the plurality of cams extend outwardly from thegenerally tubular body so as to release the wire to withdraw the wirefrom the bore of the generally tubular body in a second directionopposite the first direction; a biasing element for biasing theplurality of cams towards the center of the bore of the generallytubular body; and a plurality of cables attached to an end of thegenerally tubular body, the plurality of cables being woven together soas to form a tube having a bore, and wherein the bore of the generallytubular body is in communication with the bore through the tube.
 10. Thewire pulling grip of claim 9, wherein the biasing element is movablebetween a first position to contact and apply a biasing force to theplurality of cams and a second position where the biasing element doesnot contact the plurality of cams and does not apply the biasing forceto the plurality of cams.
 11. The wire pulling grip of claim 10, whereinthe biasing element is disposed around an exterior of the generallytubular body.
 12. The wire pulling grip of claim 11, wherein the biasingelement is disposed around a portion of the generally tubular body whichis tapered such that the biasing element reduces in size as the biasingelement moves axially towards the plurality of cams.
 13. The wirepulling grip of claim 9, wherein each of the plurality of cams isdisposed in a slot formed through the generally tubular body, andwherein the biasing element extends around the generally tubular body soas to contact the plurality of cams.
 14. The wire pulling grip of claim9, wherein the plurality of cams are spaced out radially about a singlepoint along the length of the generally tubular body.
 15. The wirepulling grip of claim 9, further comprising a loop for connecting thewire pulling grip to a pulling line, the loop being disposed at an endof the tube opposite the generally tubular body.
 16. The wire pullinggrip of claim 15, wherein the loop is formed from a proximal end of theplurality of cables.
 17. A wire pulling grip comprising: a body having abore therethrough, the body encompassing the bore; a plurality of camspivotably attached to the body, the plurality of cams being pivotablerelative to the body between a first position where the plurality ofcams extend into the bore of the body so as to grip a wire inserted in afirst direction into the bore of the body and a second position wherethe plurality of cams extend outwardly from the bore and the body so asto release the wire to withdraw the wire from the bore of the body in asecond direction opposite the first direction; a biasing element forbiasing the plurality of cams towards the bore of the body; and a tubeformed of woven wires attached to the body, the tube defining a lumenwhich is aligned with the bore of the body.
 18. The wire pulling grip ofclaim 17, wherein the biasing element is movable to a position where thebiasing element does not contact the plurality of cams and does not biasthe plurality of cams.